Final answer:
Jason is likely in the stage of resistance of the general adaptation syndrome, where his body has adapted to ongoing stress but still remains on alert, leading to symptoms like tension headaches and eating difficulties.
Step-by-step explanation:
Based on the symptoms of tension headaches, trouble eating, and a period of stress spanning multiple weeks, it sounds like Jason is experiencing the stage of resistance in the general adaptation syndrome (GAS). In this stage, the initial shock of the alarm reaction has worn off, and the body has adapted to the stressor. Yet, the body remains on alert and the physiological reactions continue, albeit with less intensity than during the alarm reaction. Jason's continued stress without relief could eventually lead him to the stage of exhaustion, where severe health problems, such as depression or a suppressed immune response, can occur.